Process of enhancing pilling resistance of textile materials

ABSTRACT

Pilling resistance of textile materials containing synthetic staple fibers is enhanced by pressing the textile materials laid on an abrasive surface carrying thereon numerous fine abrasive grains with sharp edges, whereby defects are formed in the staple fibers distributed on the textile fiber surface by the sharp edges.

United States Patent 1191 Ito et a1. July 15, 1975 [5 PROCESS OFENHANCING PILLING 2.053.778 9/1936 Elan 56/28 2.253.558 8/1941 urtin6/28 RESISTANCE OF TEXTILE MATERIALS 2.253.559 8/l94lCurtin............. 26/28 [75] Inventors: Toshio Ito; TokuhisaMiyamatsu; 1 17.170 11/1952 Mulholland 26/28 Iwao Miyashita, all ofNagoya. 2.706.845 4/1955 Swan 26/! Japan 3.068.544 [2/[962 Connell etal. 26/28 3.523.346 8/1970 B len e! a! 26/28 X Assigneei MitsubishiRayon Company Limited, 3.553.801 1/1971 H dlcy 26/28 Tokyo Japan FOREIGNPATENTS OR APPLIC TIONS A [22] June 1972 374.600 6/1962 Japan 26/! [21]Appl. No.: 268,142

Primary Examiner-Robert R. Mackey [30] Foreign Appucafion p i i DataAttorney. Agent. or Firm-Armstrong. Nikaido &

July 5. 1971 Japan 46-48819 wegne' July 8. l97l Japan 4660487 [57]ABSTRACT [52] U.S. Cl. 26/28; 26/] pining resistanc of textile materialscontaining [511 f Cl D066 11/00 006C 29/09 thetic staple fibers isenhanced by pressing the textile [58] held of Search 26/28 69 materialslaid on an abrasive surface carrying thereon 51/80 80 01/23 numerousfine abrasive grains with sharp edges. whereby defects are formed in thestaple fibers distrib- [56] References cued uted on the textile fibersurface by the sharp edges.

UNITED STATES PATENTS 295.986 4/1884 Crooke et a] 101/23 6 9 Draw FguresPROCESS OF ENHANCING FILLING RESISTANCE OF TEXTILE MATERIALS BACKGROUNDOF THE INVENTION The present invention relates to a process of enhancingpilling resistance of textile materials containing synthetic staplefibers; more particularly, it relates to a process of enhancing pillingresistance of spun yarns, woven fabrics and knitted fabrics containingsynthetic staple fibers.

Generally, it is known that textile materials such as spun yarns, andwoven knitted fabrics containing the spun yarns, have largedisadvantages in that numerous pills are formed on their surfaces duringwearing. This is especially true in the cases where high tenacity staplefibers, such as synthetic fibers and highly crimped fibers, are used forforming the textile material. These textile materials have a highsoftness due to the low frictional property of the staple fibers and itis very difficult to avoid pill-formation on the textile materialsurface. The pills formed on the textile material surface result in anundesirable appearance and feel to the hand.

The mechanism of the pill-formation is not completely known at thepresent time. However, it seems that when the textile material surfaceis rubbed against itself or other surfaces during wearing, fluffs, fluesand dusts on the surface are entangled with each other so as to frizz afew little tufts. These little tufts draw out the fibers entangled withthem from the textile material and build up into large pills.

If the staple fibers have a low tenacity or strength, they are broken byrubbing during wearing and removed from the textile material surfacewithout pillformation. However, the synthetic fibers usually have a hightenacity and tend to form numerous pills on the textile materialsurface.

In order to prevent the textile material from the undesirablepill-formation, various methods of enhancing the pilling resistance ofthe textile materials are provided, as follows.

I. The tenacity and elongation of the staple fibers to be formed intothe desired textile material are reduced. The little tufts initiallyformed on the textile material surface are, therefore, easily removedfrom the surface before they build up into pills.

2. The frictional resistance of the fibers to each other is increased inorder to enhance the resistance of the fiber against draw out from thetextile material.

3. Staple fibers having a small number of crimps are used for formingthe textile material. Such small number of crimps is effective forpreventing the undesirable entanglements of the fibers with each other.

In the first method, the low tenacity fibers are produced by a specialfiber-forming method or by treating the textile material with specialchemicals. The former method results in difficulty in the spinning ofthe low tenacity staple fibers. The latter method results indisadvantages such as unevenness in dyeing characteristics andundesirable touch of the textile material.

In the second method, the high frictional resistance of the fibersresults in an undesirable feel to the touch, high stiffness andlimitation of use. Therefore, the second method is merely valuable forlimited fabrics and uses only.

In the third method, the small number of crimps on the fibers results indifficulty in the spinning of yarns.

The object of the present invention is to provide a process of enhancingpilling resistance of textile materials containing staple fibers,without a resultant undesirable feeling to the hand and appearance.

SUMMARY OF THE INVENTION The object of the present invention can beaccomplished by the process wherein at least one surface of a textilematerial containing staple fibers is brought into contact with anabrasive surface, carrying thereon numerous abrasive grains having sharpedges. The textile material is pressed on the abrasive surface so as toform defects in the fibers distributed on the textile material surfacewith the sharp edges.

The scratched fibers on the textile material surface have a lowtenacity. Therefore, when the textile material surface is rubbed, thescratched fibers are easily broken and removed from the surface withoutpillformation.

In the process of the present invention, the pressing may beintermittently effected between two flat pressing faces, wherein atleast one face is covered by an abrasive layer containing numerous fineabrasive grains. Also, the pressing may be continuously effected betweena pair of nipping rollers, wherein at least one roller is covered by anabrasive layer containing numerous fine abrasive grains. In this case,the nipping rollers may rotate either at the same peripheral velocity aseach other or at different peripheral velocities from each other. Whenone roller rotates at a different peripiteral velocity from that of theother, it is preferable that the ratio of larger to smaller peripheralvelocities is greater than 1.0 but not exceeding 1.5.

By the pressing in accordance with the process of the present invention,the textile material is enhanced in pilling resistance withoutundesirable changes of appearance and feeling to the hand or touch.However, its toughness is slightly lowered.

When the textile material is pressed onto the abrasive surface, carryingthereon numerous fine abrasive grains having sharp edges, the fiberslocated on the textile material surface are scratched by the sharp edgesof the abrasive grains so as to form defects. These defects formweaknesses or incisions such as cuts, cracks, scratches or recesses, onthe fiber surface. The weakness of the pressed fibers can be controlledby adjusting size and density of the abrasive grains. Also, in order toavoid a large reduction in the strength of the textile material duringpressing, the material may be laid on a cushiony material such anelastic sheet; for example, a rubber sheet, polyurethane sheet or othersynthetic elastic material sheet. It also may be laid on a thick fibroussheet, for example, felt or thick cloth.

The abrasive surface usable for the present invention carries thereonnumerous fine abrasive grains, having a hardness greater than the fiberswith sharp edges to scratch the fibers. Such abrasive surface may be anabrasive sheet such as sand paper or sand cloth, on which numerousabrasive grains are fixed with a binder. It also may be an abrasiveroller wherein an abrasive layer is formed on a metal roller, a naturalor artificial grinding wheel.

The abrasive grains preferably consist of metallic material having aShore hardness of 50 or more, for example, a carbon steel quenched by ahigh frequency induction process, or they may consist of an inorganicmaterial having of a hardness of 5 or more in Mohs scale of hardness.Examples of such inorganic materials are diamond, boron carbide, siliconcarbide and crystallized alumina; molten zircon, garnet, jade and rockcrystal; silica, molten quartz, orthoclase and apatite; or mixtures oftwo or more of these materials. The abrasive grains usable for theprocess of the present invention preferably have a size of l6 to 250p,and are preferably distributed in a density of 50 grains/cm or more.

The pressing condition in the process of the present invention iscontrolled in accordance with the kind and form of the textile materialand the abrasive surface.

The process of the present invention may be applied to synthetic fiberssuch as polyamide, polyester, polyacrylonitrile, polypropylene andpolyvinyl alcohol fibers; semi-synthetic fibers such as triacetate anddiacetate fibers; generated fibers such as rayon and cupra fibers;natural fibers such as wool and cotton. Also, the process of the presentinvention may be applied to web, tow, silver, roving yarn; non-wovenfabric, spun yarn, woven fabric and knitted fabric containing the staplefiber spun yarn.

BRIEF DESCRIPTION OF THE DRAWINGS The features and advantages of theprocess of the present invention will be apparent upon reading thefollowing specification referring to the accompanying drawings in which:

FIG. 1 is a schematic view of an embodiment of a pressing apparatususable for intermittently performing the process of the presentinvention,

FIGS. 2 to 8, respectively, are side views of embodiments of pressingapparatus usable for continuously performing the process of the presentinvention, and

FIG. 9 is a schematic view of an embodiment of a continuous pressingapparatus for a textile yarn.

The pressing apparatus as shown in FIG. 1 is useful for pressing piecegoods of textile material such as sweaters, skirts and dresses inaccordance with the process of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, apressing apparatus I is composed of a pair of flat pressing plates 2 and3. The

upper pressing plate 2 has a lower flat abrasive layer 4 and isconnected to a driving means (not shown in the drawing) through a shaft5. The lower pressing plate 3 has a flat upper surface 6 for supportingthereon a piece good 7 of the textile material. If it is necessary, theupper surface 6 of the lower pressing plate 3 may be covered by acushiony sheet 8, such as a rubber sheet or felt sheet.

The abrasive layer 4 contains numerous abrasive grains. The upperpressing plate 2 is pushed down by the driving means and presses thepiece good 7 on the lower pressing plate 3 which is non-movable. By thispressing action the upper side of the piece good 7 is brought intocontact with the abrasive surface 4 and its pilling resistance isenhanced. Next, the opposite side of the piece good 7 is put on theupper surface 6 of the lower pressing plate 3 so that the unscratchedsurface of the piece good 7 comes into contact with the abrasive surface4 when pressed by the upper pressing plate 2.

In the apparatus of FIG. 1, the upper surface 6 of the lower pressingplate 3 may be covered by an abrasive layer instead of the cushionysheet 8. In such case, both the upper and lower sides of the piece goods7 are simultaneously pressed by the abrasivesurfaces.

The apparatus as shown in FIGS. 2 to 9 are useful for continuouslypressing textile material such as tow, silver, web, roving, fabric andyarn.

Referring to FIG. 2 the continuous pressing apparatus 21 is composed oftwo rotatable rollers 22 and 23. The upper roller 22 has acore roller 25surrounded by an abrasive paper 24 which contains numerous abrasivegrains. The lower roller 23 has a smooth surface 26. A continuoustextile material 27, such as fabric or yarn, is supplied into thepressing apparatus 21 and continuously nipped between the upper andlower rollers 22 and 23. One side surface of the textile material whichhas contacted the abrasive paper 24 is enhanced in pilling resistance.

Referring to FIG. 3, the pressing apparatus 31 is composed of upper andlower rollers 32 and 33. Each roller respectively has abrasive paper 34,35 surrounding it. When a textile material 36 is continuously pressedbythe pressing apparatus 31, both the upper and lower side surfaces of thetextile material 36 are simultaneously brought into contact with theabrasive papers 34, 35 and thereby enhanced in pilling resistance.

The apparatus 41 as shown in FIG. 4 is provided with 21 upper roller 42,lower roller 43, a tension roller 44 and an abrasive cloth 45. When theupper or lower roller 42 or 43 is driven the abrasive cloth 45 endlesslycirculates around the upper roller 42 and tension roller 44 whilepressing the textile material 46. The tension roller 44 is movable so asto keep the abrasive cloth 45 at a predetermined tension. That is, inthe pressing apparatus of FIG. 4, the abrasive cloth 45 is separablefrom the upper roller 42.

In the pressing apparatus 51 of FIG. 5, an upper roller 52is made from agrinding wheel and a lower roller 53 has a smooth surface. A textilematerial 54 is pressed between the upper and lower rollers 52 and 53.

Referring to FIG. 6, a pressing apparatus 61 is provided with an upperroller 62 and a lower roller 63. The upper roller 62 has a core roller64 and a surrounding abrasive layer 65, which consists of numerousabrasive grains and a binder for fixing the abrasive grains. The lowerroller 63 has a core roller 66 and a cushiony layer 67. The cushionylayer 67 consists of an elastic or compressible material and surroundsthe core roller 66. When a textile material 68 is pressed between theabrasive layer 65 and the cushiony layer 67, a portion of the pressureis absorbed by the cushiony layer 67. This prevents scratches in thetextile material which are too large.

The pressing of the present invention may be applied to the textilematerial only once under a suitable pressure. However, the pressing maybe applied to the textile material twice or more under a relatively lowpressure. Such repeated pressing is valuable for enhancing the pillingresistance of the textile material with a small decrease of the tenacityand elongation.

The apparatus as shown in FIGS. 7 through 9 are useful for continuouslyand repeatedly pressing the textile material.

Referring to FIG. 7, the pressing apparatus 71 is provided with an upperroller 72, a middle roller 73 and a lower roller 74. The upper roller 72is composed of a core roller a and a cushiony layer 760; the middleroller 73 is composed of a core roller 75b and an abrasive layer 77; thelower roller 74 is composed of a core roller 75c and a cushiony roller76b. A textile material is first pressed between the lower roller 74 andthe middle roller 73, after which it is pressed a second time betweenthe middle roller 73 and the upper roller 72. In this case, one sidesurface of the textile material is pressed twice by the abrasivesurface.

Referring to FIG. 8, the pressing apparatus 81 has a large roller 82which is composed of a core roller 83 and a surrounding abrasive cloth84 and three small rollers 85a, 85b, 850. Each of the three smallrollers is composed of a core roller 86a, 86b, 86c and a cushiony layer87a, 87b, 87c surrounding the core roller. When the large roller 83rotates, a textile material 88 is successively pressed three timesbetween the abrasive cloth 84 of the large roller 82 and the smallrollers 85a, 85b, 85c.

The pressing apparatus as illustrated in FIG. 9 is useful forsuccessively pressing a textile yarn twice or more. Referring to FIG. 9,the pressing apparatus 91 is provided with a guide roller 92, an upperroller 93 and a lower roller 94. The guide roller 92 is located in frontof the upper and lower rollers 93 and 94 and in parallel with them. Theupper roller 93 consists of a grinding wheel and thus has an abrasivesurface on its periphery. The lower roller 94 is provided with a coreroller 95 surrounded by a cushiony layer 96. A textile yarn 97 issupplied to the upper and lower rollers 93 and 94 through the guideroller 92 and wound around the guide roller 92 and the lower roller 94once or more times (twice in FIG. 9). When the upper or lower roller 93or 94 rotates, the textile yarn is pressed twice or more (three times inFIG. 9) between the upper and lower rollers 93 and 94.

In the process of the present invention, the pressure to be applied tothe textile material is adjusted in consideration of the kind, form andthickness of textile material, kind, size and density of the abrasivegrains on the abrasive surface; diameter of the pressing roller, andutilization of the cushiony roller. When the textile material is pressedwith an abrasive surface without cushion, the pressure is adjusted intoa relatively low value in order to prevent breakage of the textilematerial.

ln the case where the textile material is pressed between two flatpressing surfaces, it is preferable that the pressure is adjusted into avalue of 180 V W or more in g/cm, wherein W represents the weight in g/mof the textile material. In this flat pressing if the cushion isutilized for absorbing a portion of the pressure, the pressure to beapplied to the textile material will be increased with the increase ofpressure absorption by the cushion.

In the case where the textile material is continuously pressed bynipping it with nipping rollers while rotating them, it is preferablethat the pressure to be applied to the textile material is adjusted to avalue of 60 Win g/cm or more, wherein W represents the weight in g/m ofthe textile material. In this continuous pressing, if one of the nippingrollers is covered by a cushion layer on its periphery, the nippingpressure will be increased with the increase of pressure absorption bythe cushion.

In the case where a textile yarn is continuously pressed using a nippingroller, the pressure to be applied to the textile yarn is preferablyadjusted to a value of 1,100 fiin g/meter 2 count or more, where Drepresents the sum of the meter count of the textile yarns applied tothe nipping roller at the same time. in this nipping, if one of thenipping rollers is surrounded by a cushion layer, the pressure to beapplied to the textile yarn will be increased with the increase of thepressure absorption of the cushion.

The process of the present invention is usually effected at a roomtemperature. However, it is preferable that the textile materialcontaining thermoplastic syn thetic fibers is pressed at a relativelyhigh temperature at which the hardness of the synthetic fibers islowered. Such pressing at a temperature higher than the room temperatureresults in a decrease of pressure necessary under which the textilematerial is enhanced in pilling resistance.

Generally, in the continuous nipping process of the present invention, apair of nipping rollers is rotated at the same peripheral velocity.However, they may rotate at a different peripheral velocity from eachother. in this case, it is preferable that the ratio of higher to lowerperipheral velocities of the two rollers is greater than I but notexceeding 1.5. If the ratio is greater than 1.5, it results inundesirable frizzing or breakage of the textile material.

The following examples illustrate the present invention but are notintended to limit the scope of the invention thereto.

1n the examples, pilling resistance, bursting strength and flat abrasionresistance of the textile material were respectively determined by themethods described below.

The pilling resistance was determined using an lCl type tester asfollows.

lCl TYPE TESTER The lCI type test consists of a rotating box lined withcork and of special rubber tubes to be put in it.

The rotating box is a regular hexahedron of an inner side 23 cm, and thelining cork has the following conditions:

Thickness Approx. 3 mm Density 0.21 t 0.03 g/cm Tensile strength 7 kg/cmor more Hardness 62 i 2 deg. (by Asker Type F) Grain size 10 to 60 meshHowever, the usable limit of cork surface lining in principle is 1,500hours rotation, and is replaced each time it is broken or worn.

Each special rubber tube is a cylinder having both ends rounded, and hasthe following parameters:

Thickness Approx. 3 mm Length Approx. mm

Outer diameter Approx. 31 mm R of both end comers Approx. 4 mm Weight 50i 2 g Hardness 42 i 5 deg. (by Asker Type C) When first used, 4 per setare put in the box and the box was rotated empty for 10 hours beforeputting it to use.

TEST METHOD Two pieces each of test piece, 10 X 12 cm, are sampled fromthe specimen, in warp direction and weft direction in the case of wovenfabric, and in Wale and course direction in the case of knit fabric, andshall be wound around the special rubber tube in the natural state so asnot to apply tension in the short side direction. The excess specimen iscut off to prevent the test pieces from being piled on together, and thetest pieces are sewn with cotton yarn, and both ends are taped so as notto cover the edge of the rubber tube with the film form adhesive tapeapprox. 1.8 cm wide. A unit of 4 of these test pieces wound around therubber tubes is put into the rotating box of the tester, and the testeris operated at the rotational speed of 60 rpm. for 10 hours in case ofthe woven fabric and hours in the case of the knit fabric. The testresult is represented by the av erage value of four test pieces.

The pilling resistance of the specimen is classified in five classes.Class 1 represents the poorest resistance and class 5 represents thehighest resistance.

The bursting strength of the textile material, that is, woven andknitted fabrics, is determined in accordance with the method defined in.118 15-1076 (Method A) using an 1C1 type tester.

The flat abrasion resistance of the textile material is determined inaccordance with the procedure defined in ASTM D1 l75-64T, lnfratedDiaphragm Method, using an abrasive paper No. 0.

EXAMPLE 1 A knitted fabric for a sweater having a weight of l g/m wasprepared from a folded yarn of 42 metric count. This consisted of ablend of 50 percent by weight of cotton and 50 percent by weight ofpolyethylene terephthalate fiber of a denier of 1.5 and a length of 48mm. An abrasive paper, carrying thereon abrasive grains consisting ofsilicon carbide, and having an average size of 24p, was superimposed onthe aboveprepared knitted fabric so as to bring an abrasive surface ofthe abrasive paper into contact with a surface of the knitted fabric.This was then pressed between a pair of flat pressing plates, as shownin FIG. 1, under a pressure of 10 kg/cm The pressed knitted fabric had apilling resistance of class 4 at the end of testing for 10 hours in the1C1 type method. Compared with this, the control knitted fabric had apilling resistance of class 2.5.

EXAMPLE 2 Plain knitted fabrics with a weight of 180 g/m were preparedfrom a high bulky folded yarn of 36 metric count using a knittingmachine of 12 gauge. The yarn consisted of acrylic fibers having adenier of 3 and a length of 51 mm.

The knitted fabrics were dyed and finished with a softening agent by aconventional process. Each knitted fabric was then superimposed onabrasive paper, carrying abrasive grains consisting of alumina andhaving an average grain size of 48p and a density of about 1,000grains/cm, so as to bring a surface of the knitted fabric into contactwith an abrasive surface of the abrasive paper. The knitted fabrics onthe abrasive surfaces were pressed 1 to 5 times by nipping them betweena metal roller, of a diameter of 350 mm, and a feltcovered roller of adiameter of 600 mm. Each roller rotated at the same peripheral velocityof 18 m/min and a pressure of 32 kglcm The knitted fabrics thus pressedwere subjected to testing of pilling resistance, bursting strength andflat abrasion resistance. The results are shown in Table l.

Table 1 Item Flat Filling Bursting abrasion Number of resistancestrength resistance pressing times (class) (kg/cm) (times) Control 1 28.2 330 As Table 1 clearly illustrates, although the knitted fabric notpressed together with the abrasive paper had a very poor resistance topilling, the pressed knitted fabrics had a high resistance to pilling.The larger the number of pressings, the higher the resistance of theknitted fabric to pilling, and the lower the bursting strength and fiatabrasion resistance. The knitted fabrics pressed five times had abursting strength of 6.6 kg/cm and a flat abrasion resistance of 240times, which are sufficient for practical use.

EXAMPLES 3 to 5 The following three fabrics were provided.

The fabric of Example 3 was a plain woven fabric having a weight of 80g/m and consisting of a blend of 30 percent by weight of cotton andpercent by weight of polyethylene terephthalate fibers.

The fabric of Example 4 was a plain stitch knitted fabric having aweight of 280 g/m, and consisting of a blend of 20 percent by weight ofpolycapramide fibers and percent by weight of wool.

The fabric of Example 5 was a double jersey having a weight of 190 g/mand consisting of a blend of 60 percent by weight of acrylic fibers and40 percent by weight of wool.

Each fabric was pressed between two metal rollers. One metal roller hada diameter of 300 mm, and was coated with a hard polyurethane resin witha rubber hardness of and a thickness of 5 mm. The other metal roller hada diameter of 150 mm, and was coated with an abrasive layer containing10 parts by weight of silicon carbide grains, having sizes of 48 to p,and 3 parts by weight of epoxy resin with a thickness of 30 mm. Thesetwo rollers rotated at the same peripheral velocity of 15 m/min, atnipping pressures as shown in Table 2.

The pressed fabrics were steam-treated by passing them through a steamerunder an ambient pressure. The fabrics were then subjected to testing ofpilling resistance for 10 hours.

From Table 2, it is obvious that the fabrics treated by the method ofthe present invention had higher pilling resistances than the controlfabrics.

EXAMPLES 6 to 8 10 the pressed fabrics had a pilling resistance higherthan that in the case where both rollers rotated at the same peripheralvelocity. However, in the former cases, the pressed fabrics had abursting strength lower than that in the latter case.

The following three fabrics were provided. The fabric Considering nowthe cases where the ratio of larger of Example 6 was a plain stitchknitted fabric prepared to smaller peripheral velocities of the tworollers was from a blend yarn. This blend consisted of 40 percent largerthan 1.5. That is, in Table 3, the cases where the by weight ofpolyethylene terephthalate fibers, of a decushion roller was inperipheral velocities of 2 and l0 nier of 3 and a length of 51 mm, and60 percent by m/min. The fabrics of Examples 6 and 7 were broken weightof rayon staple, of a denier of 2.5 and a length during the pressing andthe bursting strength of the of 51 mm. pressed fabric of Example 8 wastoo low to use in prac- The fabric of Example 7 was a tubular knittedfabric tice. with a Milano rib structure prepared from a blend yarn.

This blend consisted of percent by weight of polycal5 EXAMPLE 9 pramidefibers, of a denier of 3 and a length of 64 mm, A folded yarn of 32metric count, having a potential and 65 percent by weight of wool. highbulkiness, was prepared from 60 parts by weight The fabric of Example 8was a plain woven fabric of regular acrylic fibers and parts by weightof high prepared from a spun yarn of 100 percent acrylic fibersshrinkage acrylic fibers of a denier of 2 and a length of of a denier of1.2 and a length of 5 1 mm. 20 51 mm. The yarn was pressed between tworollers, hav

Each fabric was pressed once between two rollers ing a peripheralvelocity of 420 m/ min under a pressure under a nipping pressure of 120kg/cm. One roller was of 1.0 kg/cm 1, 2, 3, 4 and 5 times. One rollerwas a an abrasive roller, wherein a metal roller having a distainlesssteel drive roller of a diameter of 120 mm and ameter of 320 mm iscovered with an abrasive paper a width of mm. The other roller was anabrasive folcarrying thereon abrasive grains, consisting of silicon 25low roller of a diameter of 100 mm and a width of 20 carbide and havingan average size of 571.4 The other mm. roller was a cushion rollercomprising a metal roller The abrasive follow roller was made of amedium having a diameter of 500 mm covered with a comdensity highhardness grinding wheel containing abrapressed felt of a thickness of 3mm. sive grains, consisting of alumina crystals, and having The abrasiveroller was rotated at a peripheral veloc- 30 an average size of p. ityof 5 m/min constant. The cushion roller was varied The pressed yarnswere converted to high bulky in peripheral velocity to 2, 3.5, 5, 7.5and 10 m/min. yarns by steaming. The bulky yarns were dyed and fin- Thepressed fabrics were subjected to the testing of pillished with asoftening agent by a conventional process ing resistance in the [Cl typemethod for l0 hours. The and, thereafter, knitted into plain stitchknitted fabric results are shown in Table 3. 35 using aknitting machineof 12 gauge. Bursting strength,

Table 3 Presed fabric at peripheral velocity of cushion roller in m/minExample No. Item Control 2.0 3.5 5.0 7.5 l0.0

Pilling resistance 6 (class) 2 4 3 4 Bursting strength (kg/cm 6.5 3.25.8 4.2 Filling resistance 7 (class) 2.5 4 3.5 4

Bursting strength (k cm) 7.! 5.0 6.5 4.8 Pil ing resistance 8 (class) L54.5 3.5 3 4 4.5

Bursting strength (kg/cm 8.2 2.8 6.2 7.4 5.4 3.6

From Table 3, it is understood that in the cases where the ratio oflarger to smaller peripheral velocities of the two rollers was greaterthan 1.0 but not exceeding 1.5,

flat abrasion resistance and pilling resistance of the resultant knittedfabrics are shown in Table 4 in comparison with the pressing times.

Table 4 Pressing Yarn Knitted fabric Experi- Nipping Number of TensileElongation Bursting Flat abrasion P illing ment pressure pressingstrength at break strength resistance resistance No. (kg/cm) times (g)(kg/cm) (time) (class) l [.0 l 690 29.8 5.79 3 I 35 2 [.0 2 650 26.05.68 304 4.5 3 1.0 3 625 24.0 5.52 305 5.0 4 L0 4 570 22.7 5.45 300 5.05 1.0 5 550 2] .3 5.30 295 5.0 6 0.25 5 690 28.2 5.72 290 1.5 7 0.5 5630 24.5 5.65 282 4.0 8 0.75 5 590 22.7 5.50 292 5.0 9 1.5 5 420 l8.04.90 293 5.0 Control 880 34.5 6.20 325 L5 Note: The testing of pillingresistance was carried out for 5 hours in the lCl type method.

From Table 4, it is seen that the pilling resistance of the knittedfabrics tended to be enhanced as the number of pressing times increased.The resultant knitted fabrics had substantially the same feel to thehand and appearance as those of the control fabric which wasnon-pressed.

Further, the same pressing was repeated five times to the same yarnsunder nipping pressures of 0.25, 0.5, 0.75 and 1.5 kg/cm. The resultantyarns, and knitted fabrics from the yarns, had the properties as shownin Table 4.

From Table 4, it is obvious that, for the yarn used in the presentinvention, it is necessary to press it under a pressure of 0.50 kg/cm orhigher with the nipping rollers used in the present example.

EXAMPLE 10 A folded yarn of metric count was prepared from 40 percent byweight of polycapramide fibers of 2 denier and 60 percent by weight ofwool and dyed by the conventional process. The yarn was pressed under acondition detailed below.

1. Nipping rollers A metallic upper roller of a diameter of 50 mm and awidth of 50 mm was covered with a polyurethane resin sheet having arubber hardness of 90 and a thickness of 1.5 mm. A metallic lower rollerhaving a diameter of 30 mm and a width of 20 mm was covered with anabrasive layer. This layer was composed of abrasive grains consisting offinely divided carbon steel, hardened by a high frequency inductionquenching method; having a Shore hardness of 60 and sizes of 34 to 80p,and a binder combining the abrasive grains in a thickness of 3 mm.

2. Nipping pressure: l.2 kg/cm 3. Peripheral velocity of rollers: 250m/min 4. Number of times of pressing: 1

The pressed yarn had a small decrease of tensile strength of 9 percent,and a small decrease of elongation at break of 10 percent, with respectto those of the original yarn. The yarn was formed into a plain stitchknitted fabric which had the same feel to the hand and appearance asthat of the original yarn. The knitted fabric had a pilling resistanceof class 4 in the testing for 5 hours in the [C] type method, and abursting strength similar to that of the knitted fabric from theoriginal yarn.

EXAMPLE 1 1 A web of a weight of 100 g/m" was prepared from regularacrylic fibers having a denier of 3 and a length of 51 mm. The web waspressed once by nipping it between a smooth metal roller and an abrasiveroller under a nipping pressure of 15 kg/cm and at a peripheral velocityof both the rollers of 10 m/min. The abrasive roller carried abrasivegrains of an average size of p consisting of silicon carbide.

60 parts by weight of the pressed acrylic fiber web was blended with 40parts by weight of non-pressed acrylic fibers. This non-pressed acrylicfiber had a shrinkage higher by 25 percent than that of the regularacrylic fibers in boiling water under atmospheric pressure. The blendwas formed into a folded yarn of 36 metric count having a high bulkinesspotential by a conventional spinning process. The yarn was heated insteam to convert it to a high bulky yarn. The yarn had the pillingresistance, tensile strength and the elongation at break as shown inTable 5.

For comparison, a yarn was prepared in the same procedure as that statedabove using the non-pressed regular acrylic fiber web. The comparisonyarn had the properties as shown in Table 5.

Note: The testing of pilling resistance was carried out for 5 hours inthe IC] type method.

We claim:

1. A process of enhancing the pilling resistance of textile fabrics,which comprises bringing at least one surface of a textile fabriccontaining synthetic staple fibers into contact with an abrasive surfaceformed on the periphery of a rotating abrasive roller, said abrasivesurface carrying thereon numerous abrasive grains having sharp edges,rotating a pressing roller in cooperation with said abrasive roller,wherein the peripheral velocity of the faster of the abrasive roller orpressure roller is 1.0 to 1.5 times the peripheral velocity of theslower of the abrasive roller or pressure roller; and simultaneouslypressing said textile fabric on said abrasive surface with said pressingroller rotating in cooperation with said abrasive roller at a pressuresuch that said abrasive roller forms incisions on the surface of thefibers distributed on the textile surface to enhance the pillingresistance without substantially changing the appearance and feel ofsaid textile fabric and while retaining acceptable fabric burstingstrength.

iony surface is formed with an elastic material.

6. A process as claimed in claim I further including rotating at least asecond pressing roller in cooperation with said abrasive roller andpressing said textile fabric on said abrasive surface with said secondpressing roller thereby forming additional incisions on the surface ofthe fibers distributed on the textile surface to further enhance thepilling resistance.

I I! i

1. A process of enhancing the pilling resistance of textile fabrics,which comprises bringing at least one surface of a textile fabriccontaining synthetic staple fibers into contact with an abrasive surfaceformed on the periphery of a rotating abrasive roller, said abrasivesurface carrying thereon numerous abrasive grains having sharp edges,rotating a pressing roller in cooperation with said abrasive roller,wherein the peripheral velocity of the faster of the abrasive roller orpressure roller is 1.0 to 1.5 times the peripheral velocity of theslower of the abrasive roller or pressure roller; and simultaneouslypressing said textile fabric on said abrasive surface with said pressingroller rotating in cooperation with said abrasive roller at a pressuresuch that said abrasive roller forms incisions on the surface of thefibers distributed on the textile surface to enhance the pillingresistance without substantially changing the appearance and feel ofsaid textile fabric and while retaining acceptable fabric burstingstrength.
 2. A process as claimed in claim 1, wherein the pressing isapplied onto said textile fabric under a nipping pressure of at least 60Square Root W in g/cm2 wherein W represents a weight in g/m2 of thetextile fabric.
 3. A process as claimed in claim 1, wherein the abrasivegrains have an average size of 16 to 150 Mu .
 4. A process as claimed inclaim 1, wherein said pressing roller has a cushiony peripheral surface.5. A process as claimed in claim 4, wherein the cushiony surface isformed with an elastic material.
 6. A process as claimed in claim 1further including rotating at least a second pressing roller incooperation with said abrasive roller and pressing said textile fabricon said abrasive surface with said second pressing roller therebyforming additional incisions on the surface of the fibers distributed onthe textile surface to further enhance the pilling resistance.